The movie debut of erstwhile Mouseketeer and current mega-diva Christina Aguilera, doesn't have a single intelligent thought in its pretty little head, but the presence of Cher as Aguilera's mentor in Burlesque, teaching her the art and science of bump'n'grind, intrigues me. Thirty years her co-star's senior, Cher has decades of experience as pop idol and global super celeb, as gossip-column staple and paparazzi prey, and has parlayed what she's never denied is a limited range, in both the vocal and thespian senses, into an estimated net worth of $600m. Everywhere Christina Aguilera has arrived in her career, Cher got there years before her; you have to wonder what advice Cher might offer the kid.

Certainly Christina took heed of Cher's approach to acting, as the older star delineated recently in the New York Times: "I never try anything more than playing who I am." The fact that "who I am" in this instance means a beloved, baroquely reupholstered, surgically worked-over female drag queen, who's been a superstar since she was Sonny Bono's underage protege and had her first hit single aged 19 … well, none of that matters in Christina's case because she's also been on the child-labour showbiz treadmill since the womb or shortly thereafter, as is the style these days, and her life – who she is – is about as normal as Cher's. As it happens, Christina is natural enough on screen, rendering some faint facsimile of her offscreen self, no doubt, and that's really all she needs. Britney Spears couldn't manage it in her accursed debut Crossroads, manically winking at everyone like she was blankly working some red carpet press-scrum while flying on major diet-pills. (Come to think of it, the ex-Mouseketeer Christina needs to emulate is Justin Timberlake; he's doing everything right.)

Given her limitations as an actor, Cher would doubtless advise her protege to surround herself with "the best talent available", meaning talent that is actually prepared to work with a neophyte who might prove a tyrant on set. In Burlesque such roles are filled by Stanley Tucci and Alan Cumming, both gaily mugging, and Kristen Bell, doing what she can with a nothing part.

It's also key that you keep that all-important gay demographic on-side. Judy Garland knew this, and so does Cher. The teenyboppers will inevitably just grow out of you, but gays, who are more insanely loyal to their idols than the Inter City Firm were to West Ham, are your first resource as a launch-pad for that mid-career comeback.

Cher's first movie, Chastity (1969), was an ill-conceived personal project of Bono's, and such a catastrophe for Cher that it put her off acting for 12 years. If Aguilera heeds that particular advice, we eagerly await her Come Back To The Five And Dime Jimmy Dean, Jimmy Dean. In about 2022.